Sometimes the music industry is a small world. For Leithauser the answer was just five blocks away from his New York home -- in the apartment of Rostam Batmanglij of Vampire Weekend.

Leithauser says the two hung out one day, and then:

"We walk into the other room, and he’s got all his recording stuff right there in his apartment. He just said: ‘Do you wanna try singing on this thing that I got?’ And I said: 'Yeah, let's try it.' He didn’t know my writing process and I didn’t know his."

The song was "1959," which Rostam had been working on for years. Leithauser came up with a new melody for it on the spot. They both loved the results

Leithauser says that moment opened the floodgates.

"It was just exciting to both of us. And it did not sound anything like either of our previous bands. It just felt like we had struck something that we needed to see where it was going," he says.

So, they kept writing. And they ended up with an entire album. It’s called “I Had A Dream That You Were Mine.”

The duo built the record on the spontaneity of that first collaboration in Rostam’s apartment. Leithauser says that took them into surprising places.

"There are songs when we started them, it was hard to imagine them ever working," he says.

One of those was “When The Truth Is.”

Leithauser says, "It was like this hip-hop groove. And I thought: 'I dont play hip-hop. I’m not gonna rap!'"

That song did make it onto the album after Leithauser got out of his comfort zone. That led to music he never would have had made with The Walkmen.

He even revived a song that he wrote for The Walkmen, called "In A Black Out." He was never happy with it, until Rostam put his musical fingerprint on it.

"The recording just sounded like something that was done in 1967 by a Leonard Cohen imitator," Leithauser says. "I was just noodling around the studio with some old thing and he was like: 'Wait, what's that?’ He brought the sound. It sounds brand new now and he made that happen."

Writers say the album is a new exciting direction for Leithauser. He’s happy and surprised that everything worked out so well.

"Being friends with somebody and wanting to work with them?" Leithauser says. "It seems like a miracle that it happened. But I’m sure that we’ll work together again."

Old friends helped Leithauser get his career to its previous high point. And a new friend got him to another one.